Recent developments in aircraft power distributions have involved a move towards the use of high voltage DC power distribution systems so as to permit a weight reduction for wiring harnesses used to distribute electrical power within an aircraft.
However such high voltage DC systems give rise to additional problems when designing aircraft power distribution systems. The high DC voltages used can, for example, lead to a decreased component lifetime, particularly for electromagnetic switches used to interrupt circuitry from drawing power from the wiring harness. Such switches are preferred to solid state devices because of their higher power ratings and ability to resist the increased switching voltages. However, even these high power devices are not immune to the effects of contact sputtering caused by arcing of the switch contacts provided therein when such contacts are separated in order to break a circuit.
Various devices and techniques have therefore been developed in an attempt to enhance the lifetime of such switchable contacts by mitigating the effects caused by the inductive energy that is stored in the circuit and which causes arcing once the contacts are separated.
For example, various known techniques may employ conventional electromagnetic switches along with additional circuitry that is used to dissipate the inductive energy of the circuit so as to minimise the energy dissipated in the electromagnetic switches themselves [1-3]. Alternatively, various non-conventional electromagnetic switches have been produced which, for example, may seek to confine the physical position of arcs in an attempt to minimise contact erosion [4].
However, whilst such techniques can enhance the useful operational lifetime of electromagnetic switches, there is still a need in the art for high voltage DC electromagnetic circuit interrupters having a further enhanced operational lifetime, particularly when used for safety critical applications such as aircraft power distribution systems.